Nissin Di622 II Flash unusual Problem

Hi there, I recently had a problem with my nissin flash.. it's the Di622 and i se it on my 60D but then one day when I changed new batteries, and pressed the power on button, instead of the usual "whining" charge, the pilot button goes green instantly but will not flash at all no matter how much time passed. only a small continuous sound is heard, other than that everything button or function works fine except it wont charge and flash.

Anyone had an encounter of this sort? any solution to that?

Thank